Currently, in a Long Term Evolution (LTE) system, a synchronization channel used for cell synchronization and cell search is located at a center of a system bandwidth. Using a system whose bandwidth is 20 MHz as an example, a frequency domain position of the synchronization channel is shown in FIG. 1. In the LTE system, before accessing the system, UE needs to search for a synchronization signal (SS). After a synchronization signal is found, the UE can determine a frequency domain position of a center frequency of the system and timing synchronization information and frequency synchronization information. To reduce complexity of searching for a synchronization signal by the UE, an LTE protocol defines that a synchronization channel needs to be located at a frequency that is an integer multiple of 100 kHz in frequency domain, for example, 2 MHz, 2.1 MHz, or 2.2 MHz. Equal intervals of 100 kHz are channel rasters of the synchronization channel in the LTE protocol.
In the future Fifth Generation (5G) mobile communication system, the system may need to send synchronization signals in a same time resource in a frequency division manner because of requirements such as multiple service co-existence or multi-beam sending, and all the synchronization signals need to be mapped to a candidate frequency domain position set of a synchronization channel. If the candidate frequency domain position set of the synchronization channel still uses the design of 100 kHz channel rasters in LTE, 100 kHz does not match a size of a frequency domain resource occupied by a physical resource block (PRB) in the 5G system, and therefore, it needs to ensure that all the synchronization signals align with boundaries of PRBs during mapping of synchronization signals, so as to minimize physical resource block overheads of the synchronization signals in the system. In this case, available mapping positions for synchronization signals are greatly limited, and an actual value of the channel raster of the synchronization channel is a least common multiple of a frequency bandwidth of the PRB and 100 kHz. In an example that the PRB occupies 180 kHz, an actual value of the channel raster of the synchronization channel is 900 kHz, and the synchronization signals need to be mapped to a position determined based on the channel raster of 900 kHz. This greatly limits available frequency domain mapping positions for the synchronization signal.